Because the isapi dlls are 32-bit (IsapiRewrite4.dll, isapi_fcgi.dll, msvcr71.dll, msvcp71.dll and libfcgi.dll), the IIS application pools for running rails need to be 32-bit instead of 64-bit (default on x64 windows OS).
1) Add the ability to set the IIS metabase flag for restricting application pools to run in 32-bit mode instead of 64-bit mode.
- Note: this limits your web server from running any 64-bit applications.
To manually change this setting, open a command prompt and execute the following:
cmd.exe /> cscript.exe %SystemDrive%\inetpub\AdminScripts\adsutil.vbs set w3svc/AppPools/Enable32bitAppOnWin64 1
Or if you have the IIS6 resource kit, run the metabase explorer and change the following:
Metabase Object => IIS://localhost/W3SVC/AppPools
Property => Enable32BitAppOnWin64
Set its value = 1 to enable 32-bit application pools.
(default is zero or not set depending upon your platform architecture)